1. Field of the Invention
The present invention relates to a motion detection device, and, more particularly, to a motion detection device using a passive infrared (PIR) motion sensor supported in an unobtrusive housing.
2. Description of the Related Art
It is known that all objects transmit a level of infrared light that varies with the temperature of the object. Taking advantage of this characteristic, passive infrared (PIR) motion sensors are used as motion detectors to detect motion of a relatively warm body that emits a relatively high level of infrared radiation, such as a human intruder or motor vehicle. If the level of infrared radiation in the vicinity of the motion detector changes by a predetermined amount, then the motion detector produces an output signal. The output signal indicates that the motion detector has sensed the motion of a warm body. In an environmental control system, the output signal may be used to trigger turning on of a light. In a security system, the output signal may be used to trigger an alarm indicating the presence of an intruder.
The PIR motion sensor is supported within a detector housing that is typically mounted on a wall of a room that is to be monitored, for example in an upper corner of the room. It is desirable to provide a detector housing that has an unobtrusive appearance.